Single protein may trigger autism

The brain's production of a single protein may be responsible for the development of autism in some adults, according to a recent US study.

The research team made its conclusion about autism after it managed to cause a genetic mutation in mice which it says causes mice to behave autistically.

The research team focused on the brain's production of a protein known as Shank3, which is found in the connections between brain cells, known as synapses.

The scientists created mice with a mutated form of Shank3, and observed that the animals tended to avoid social interaction.

The mice also repeatedly self-groomed and hurt themselves in the process.

Analysis of the animals' brains revealed defects in the circuits that connect two different areas of the brain, the cortex and the striatum, which are important for the regulation of social interactions and behaviours.

Carol Povey, director of the National Autistic Society's Centre for Autism, said that while animal research helped advance people's understanding of the role of genetics it was only a small part of the picture when it cames to understanding autism.

Guoping Feng, a researcher at Duke University "Our study demonstrated that Shank3 mutation in mice lead to defects in neuron-to-neuron communications".

He said the findings and the mouse model had allowed researchers to work out the precise neural circuit defects responsible for the abnormal behaviours.

Guo said the approach could lead to new strategies and targets for developing treatment.

However, not all autistic patients have Shank3 mutations.

Scientists are still unsure about exactly how biochemistry, inheritance and the environment combine to produce autism in humans.

They have, however, identified hundreds of genes linked to the condition.

Autism patients may only have one or a few of the possible mutations, making drugs hard to develop.

The team concluded that Shank3 played a key role in the establishment of many brain circuits that give rise to social behaviour.

Feng believes other cases could be linked to disruptions to other proteins that control synaptic function.

In that case it should be possible to develop treatments that restore synaptic function, regardless of which protein is defective in a given person.